185 research outputs found
An integrated dexterous robotic testbed for space applications
An integrated dexterous robotic system was developed as a testbed to evaluate various robotics technologies for advanced space applications. The system configuration consisted of a Utah/MIT Dexterous Hand, a PUMA 562 arm, a stereo vision system, and a multiprocessing computer control system. In addition to these major subsystems, a proximity sensing system was integrated with the Utah/MIT Hand to provide capability for non-contact sensing of a nearby object. A high-speed fiber-optic link was used to transmit digitized proximity sensor signals back to the multiprocessing control system. The hardware system was designed to satisfy the requirements for both teleoperated and autonomous operations. The software system was designed to exploit parallel processing capability, pursue functional modularity, incorporate artificial intelligence for robot control, allow high-level symbolic robot commands, maximize reusable code, minimize compilation requirements, and provide an interactive application development and debugging environment for the end users. An overview is presented of the system hardware and software configurations, and implementation is discussed of subsystem functions
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A combination of norethindrone acetate and leuprolide acetate blocks the gonadotrophin-releasing hormone agonistic response and minimizes cyst formation during ovarian stimulation
A protocol utilizing both leuprolide acetate (LA) and norethindrone acetate (NETA) in subjects undergoing ovarian suppression prior to follicle aspiration proved more effective than LA alone in reducing the incidence of ovarian cyst formation without affecting clinical outcome. Patients (n = 105) undergoing ovarian stimulation followed by follicle aspiration and in-vitro fertilization (IVF) were prospectively randomized and studied. Study measures included ovarian suppression days, days of human meno-pausal gonadotrophin (HMG) stimulation, serum oestradiol concentrations, number of cycles developing de novo cysts (> 15 mm), number of induced flare responses (day 8 oestradiol 5=50 pg/ml), number of office visits, total dose exogenous gonadotrophins, number oocytes retrieved, and clinical pregnancy and delivery rates per retrieval. Patients undergoing FVF received either LA alone (n = 58; controls) or LA and NETA (n = 47; study group) for the first 8 days of their cycle. Results comparing NETA/LA versus LA demonstrated: serum oestradiol 20.7 ± 3.9 versus 573 ± 9.4 pg/ml respectively on day 8 of ovarian suppression (P 15 mm compared to 15 (25.9%) controls (P < 0.01). No differences were observed for days of stimulation, peak oestradiol attained, total dosage of exogenous gonadotrophins, or number of aspirated oocytes. Neither were there differences in the clinical pregnancy (26.8 versus 22.6%) nor in delivery rates (19.5 versus 20.8%). We conclude that the addition of NETA to LA enhances ovarian suppression and lessens ovarian cyst formation, thereby significantly decreasing the overall cost per cycle
Quantitative transcription factor binding kinetics at the single-molecule level
We have investigated the binding interaction between the bacteriophage lambda
repressor CI and its target DNA using total internal reflection fluorescence
microscopy. Large, step-wise changes in the intensity of the red fluorescent
protein fused to CI were observed as it associated and dissociated from
individually labeled single molecule DNA targets. The stochastic association
and dissociation were characterized by Poisson statistics. Dark and bright
intervals were measured for thousands of individual events. The exponential
distribution of the intervals allowed direct determination of the association
and dissociation rate constants, ka and kd respectively. We resolved in detail
how ka and kd varied as a function of 3 control parameters, the DNA length L,
the CI dimer concentration, and the binding affinity. Our results show that
although interaction with non-operator DNA sequences are observable, CI binding
to the operator site is not dependent on the length of flanking non-operator
DNA.Comment: 34 pages, 10 figures, accepted by Biophysical Journa
A practical review of energy saving technology for ageing populations
Fuel poverty is a critical issue for a globally ageing population. Longer heating/cooling requirements combine with declining incomes to create a problem in need of urgent attention. One solution is to deploy technology to help elderly users feel informed about their energy use, and empowered to take steps to make it more cost effective and efficient. This study subjects a broad cross section of energy monitoring and home automation products to a formal ergonomic analysis. A high level task analysis was used to guide a product walk through, and a toolkit approach was used thereafter to drive out further insights. The findings reveal a number of serious usability issues which prevent these products from successfully accessing an important target demographic and associated energy saving and fuel poverty outcomes. Design principles and examples are distilled from the research to enable practitioners to translate the underlying research into high quality design-engineering solutions
Structure of a Chaperone-Usher Pilus reveals the molecular basis of rod uncoiling
Types 1 and P pili are prototypical bacterial cell-surface appendages playing essential roles in mediating adhesion of bacteria to the urinary tract. These pili, assembled by the chaperone-usher pathway, are polymers of pilus subunits assembling into two parts: a thin, short tip fibrillum at the top, mounted on a long pilus rod. The rod adopts a helical quaternary structure and is thought to play essential roles: its formation may drive pilus extrusion by preventing backsliding of the nascent growing pilus within the secretion pore; the rod also has striking spring-like properties, being able to uncoil and recoil depending on the intensity of shear forces generated by urine flow. Here, we present an atomic model of the P pilus generated from a 3.8 Å resolution cryo-electron microscopy reconstruction. This structure provides the molecular basis for the rod’s remarkable mechanical properties and illuminates its role in pilus secretion
Boron-Bearing Kornerupine from Fiskenaesset, West Greenland: A Reexamination of Specimens from the Type Locality
In 1884, Lorenzen proposed the formula MgAI2SiO6 for his new mineral kornerupine from Fiskenæsset and did not suspect it to contain boron. Lacroix and de Gramont (1919) reported boron in Fiskenæsset kornerupine, while Herd (1973) found none. New analyses (ion microprobe mass analyser and spectrophotometric) of kornerupine in three specimens from the type locality, including the specimens analysed by Lorenzen and Herd, indicate the presence of boron in all three, in amounts ranging from 0.50 to 1.44 wt.% B203, e.g. (Li0.04 Na0.01 Ca0.01) (Mg3.49 Mn0.01 Fe0.17 Ti0.01 Al5.64)Σ9.30 (Si3.67 Al1.02 B0.31)Σ5 O21 (OH0.99 F0.01) for Lorenzen\u27s specimen. Textures and chemical compositions suggest that kornerupine crystallized in equilibrium in the following assemblages, all with anorthite (An 92-95) and phlogopite (XFe = atomic Fe/(Fe + Mg) = 0.028-0.035): (1) kornerupine (0.045)-gedrite (0.067); (2) kornerupine (0.038-0.050)-sapphirine (0.032-0.035); and (3) kornerupine (0.050)-hornblende. Fluorine contents of kornerupine range from 0.01 to 0.06%, of phlogopite, from 0.09 to 0.10%. In the first assemblage, sapphirine (0.040) and corundum are enclosed in radiating bundles of kornerupine; additionally sapphirine, corundum, and/or gedrite occur with chlorite and pinite (cordierite?) as breakdown products of kornerupine. Kornerupine may have formed by reactions such as: gedrite + sapphirine + corundum + B203 (in solution) + H20 = kornerupine + anorthite + Na-phlogopite under conditions of the granulite facies. Boron for kornerupine formation was most likely remobilized by hydrous fluids from metasedimentary rocks occurring along the upper contact of the Fiskenæsset gabbro-anorthosite complex with amphibolite
Quail Genomics: a knowledgebase for Northern bobwhite
<p>Abstract</p> <p>Background</p> <p>The Quail Genomics knowledgebase (<url>http://www.quailgenomics.info</url>) has been initiated to share and develop functional genomic data for Northern bobwhite (<it>Colinus virginianus</it>). This web-based platform has been designed to allow researchers to perform analysis and curate genomic information for this non-model species that has little supporting information in GenBank.</p> <p>Description</p> <p>A multi-tissue, normalized cDNA library generated for Northern bobwhite was sequenced using 454 Life Sciences next generation sequencing. The Quail Genomics knowledgebase represents the 478,142 raw ESTs generated from the sequencing effort in addition to assembled nucleotide and protein sequences including 21,980 unigenes annotated with meta-data. A normalized MySQL relational database was established to provide comprehensive search parameters where meta-data can be retrieved using functional and structural information annotation such as gene name, pathways and protein domain. Additionally, blast hit cutoff levels and microarray expression data are available for batch searches. A Gene Ontology (GO) browser from Amigo is locally hosted providing 8,825 unigenes that are putative orthologs to chicken genes. In an effort to address over abundance of Northern bobwhite unigenes (71,384) caused by non-overlapping contigs and singletons, we have built a pipeline that generates scaffolds/supercontigs by aligning partial sequence fragments against the indexed protein database of chicken to build longer sequences that can be visualized in a web browser. </p> <p>Conclusion</p> <p>Our effort provides a central repository for storage and a platform for functional interrogation of the Northern bobwhite sequences providing comprehensive GO annotations, meta-data and a scaffold building pipeline. The Quail Genomics knowledgebase will be integrated with Japanese quail (<it>Coturnix coturnix</it>) data in future builds and incorporate a broader platform for these avian species. </p
Biofuel Blending Reduces Aircraft Engine Particle Emissions at Cruise Conditions
Aviation aerosol emissions have a disproportionately large climatic impact because they are emitted high in the relatively pristine upper troposphere where they can form linear contrails and influence cirrus clouds. Research aircraft from NASA, DLR, and NRC Canada made airborne measurements of gaseous and aerosol composition and contrail microphysical properties behind the NASA DC-8 aircraft at cruise altitudes. The DC-8 CFM-56-2C engines burned traditional medium-sulfur Jet A fuel as well as a low-sulfur Jet A fuel and a 50:50 biofuel blend. Substantial, two-to-three-fold emissions reductions are found for both particle number and mass emissions across the range of cruise thrust operating conditions. These observations provide direct and compelling evidence for the beneficial impacts of biojet fuel blending under real-world conditions
The Lost Library of Anne Conway
The philosopher Anne Conway (1631-1679) owned a large library, and her reading and book ownership shaped her intellectual life in distinctive ways. Until now, however, almost nothing has been known about the details of her reading or her book collection. Current scholarship assumes that her library, like that of her husband, the third Viscount Conway (c. 1623–1683), was lost or dispersed after her death. This article presents previously unrecognised evidence of Conway’s book ownership, and identifies, for the first time, the only books currently known to survive from her personal library. It traces their path to their current location in the Old Library of Jesus College, Cambridge, through the library of the soldier, book collector, and Cambridge Fellow Francis Sterling (c. 1652-1692). The article demonstrates that the newly identified books reveal previously unknown patterns of intellectual exchange amongst Conway’s family, and argues that they have significant implications for our understanding of her early intellectual development
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